... Rob Arthur and I showed last year that despite significant overlap in the Triple-A and MLB player pools, the home run explosion hadn’t yet extended to the upper levels of the minor leagues, which use balls manufactured in China that differ from the Costa Rica–made MLB ball. And fourth, the homers have been distributed disproportionately, flattening the distance between hitters on the home run leaderboard rather than inflating any individual totals to record highs. Less powerful hitters have derived bigger benefits, which seems consistent with the fact that there’s a fly-ball-distance sweet spot where balls become much more likely to turn into homers. Players who previously had warning-track power might have more to gain from adding extra feet to their flies and regularly reaching that sweet spot than the elite sluggers who were already comfortably clearing the fence.
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